SOLUTION: I thought you used the formula -b+-sqroot b^2-4ac/2a My answer did not look right, please help! Solve. 15x^4-11x^2+2=0

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equation Customizable Word Problems -> SOLUTION: I thought you used the formula -b+-sqroot b^2-4ac/2a My answer did not look right, please help! Solve. 15x^4-11x^2+2=0      Log On


   

Question 374485: I thought you used the formula -b+-sqroot b^2-4ac/2a My answer did not look right, please help!
Solve.
15x^4-11x^2+2=0
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation ax%5E2%2Bbx%2Bc=0 (in our case 15x%5E2%2B-11x%2B2+=+0) has the following solutons:

x%5B12%5D+=+%28b%2B-sqrt%28+b%5E2-4ac+%29%29%2F2%5Ca

For these solutions to exist, the discriminant b%5E2-4ac should not be a negative number.

First, we need to compute the discriminant b%5E2-4ac: b%5E2-4ac=%28-11%29%5E2-4%2A15%2A2=1.

Discriminant d=1 is greater than zero. That means that there are two solutions: +x%5B12%5D+=+%28--11%2B-sqrt%28+1+%29%29%2F2%5Ca.

x%5B1%5D+=+%28-%28-11%29%2Bsqrt%28+1+%29%29%2F2%5C15+=+0.4
x%5B2%5D+=+%28-%28-11%29-sqrt%28+1+%29%29%2F2%5C15+=+0.333333333333333

Quadratic expression 15x%5E2%2B-11x%2B2 can be factored:
15x%5E2%2B-11x%2B2+=+%28x-0.4%29%2A%28x-0.333333333333333%29
Again, the answer is: 0.4, 0.333333333333333. Here's your graph:
graph%28+500%2C+500%2C+-10%2C+10%2C+-20%2C+20%2C+15%2Ax%5E2%2B-11%2Ax%2B2+%29